The present invention relates to introducing a fluid additive into a relatively more viscous fluid particularly when the fluid is a food composition extrudate. Specifically, in one aspect, the present invention relates to dividing a fluid food extrudate mass flow into a plurality of subflows each traveling through their own corresponding passageway. Each subflow is then cross-sectionally partitioned wherein a fluid additive is dispersed throughout each subflow.
Food products are commonly in some type of fluid form during and/or after processing. Extruders are often used to process various types of food products. Extruders are desirable because they can produce a large amount of a fluid food, which may be a food dough, for example, and more specifically a cooked food cereal dough in a short period of time. Moreover, it is advantageous to divide the fluid food extrudate or other mass food flow into a multiplicity of extrudate subflows by splitting the mass flow and directing these extrudate subflows into and through a plurality of corresponding separate passageways. This enables each extrudate substream to be further manipulated and processed. For example, an additive injection device can then incorporated into each passageway thereby enabling a suitable type and quantity of fluid additive to be introduced into the extrudate subflow. Additives can be introduced to enhance the flavor, color or texture of the final food product. Thus, either a single food product with one or more desired characteristics (i.e., a ready-to-eat cereal of a desired color or with an assortment of differently flavored and/or colored pieces, for example) or a variety of distinct food products (i.e., an array of distinct snack foods derived from the common extrudate mass flow) can be produced by dividing the extrudate mass flow into subflows.
However, obtaining a desired degree of mixing or a homogenous mixture after introducing a fluid additive into a relatively viscous fluid food extrudate subflow or other fluid food product is troublesome. Typical food dough extrudates may have a viscosity in the range of from about 200,000 to 1,000,000 centipoise, for example. Upon introduction into a fluid food extrudate, a typically less viscous fluid additive (such as a colorant or flavorant) has a tendency to migrate to the exterior periphery of the extrudate where the additive tends to pool without blending with the food extrudate. This pooling at the extrudate""s periphery prevents adequate blending of the additive throughout the extrudate mass by static mixers or other mixers located downstream from the additive injection point leaving undesirable pockets or areas of relatively high additive concentration in the extrudate mass.
Dividing a fluid food extrudate mass flow into subflows and subsequently introducing a fluid food additive has inherent shortcomings in addition to pooling or insufficient mixing. Introducing an additive injection device into the cross-sectional flow of the extrudate substream can substantially increase the pressure drop along the length of the passageway where the injection device is present. This increases the overall resistance in the system. When the original extrudate mass flow is divided into a plurality or many subflows, each travelling through a corresponding separate passageway, the additional energy required to drive the highly viscous fluid food extrudate to system""s end can be substantial. Moreover, providing an independent additive supply for each additive injection device incorporated within each passageway makes it difficult to obtain a uniform introduction of additive in each of a plurality of extrudate subflow passageways.
A need exists to more uniformly introduce the same amount of additive across a plurality of food extrudate subflows travelling through separate passageways. A need also exists to more effectively reduce pooling when additive is introduced. Finally, a need exists for an additive injector device that can be easily and readily cleaned and/or sanitized.
To avoid peripheral pooling, fluid additives are introduced by inserting an additive injector into the passageway perpendicular to the longitudinal axis of the fluid food extrudate subflow. This partitions the subflow mass prior to the introduction of the additive. Splitting or partitioning has the advantage of reducing the amount of static mixing required to blend the additive in the passageway which consequently lowers the overall pressure drop of the device. In this configuration, the additive is dispersed in the center of the extrudate mass subflow thereby offsetting the tendency of the additive to migrate and pool on the extrudate""s outer periphery.
In accordance with one aspect of the present invention, an apparatus for injecting a fluid additive into a viscous fluid food flow stream is provided. The apparatus includes a passageway having an interior and an exterior, including an interior wall, which passageway is suitable to accommodate a fluid food flow, which may be a cooked cereal dough, for example, or other material, through the interior of the passageway. Structure is disposed in the passageway for injecting a fluid additive into the fluid food flow in the passageway. The structure in accordance with the invention for injecting the fluid additive can be streamlined to minimize the pressure drop across the injecting structure. In addition, the injecting device may include structure to preventing fluid injected by the injector from contacting the interior wall of the passageway. Such action prevents unwanted pooling or accumulation of additive fluid at the outer portions of the fluid food stream, which can result in an unacceptable or undesirable product.
The fluid additive can be any fluid additive as desired, and may include a colorant, flavor, food supplement or any other desired fluid food additive.
In accordance with another aspect of the present invention, the structure for injecting the fluid additive into the relatively viscous fluid food stream includes a fluid additive manifold located within the passageway, which manifold may be mounted within the passageway. The manifold may be contained within an annular body or other shaped body or portion thereof as desired. A plurality of elongated ribs extend from the manifold and extend transversely across at least a portion of the passageway. Each of the ribs may have a downstream surface and a streamlined upstream surface to minimize pressure loss across the injector device. Generally, the manifold will have an internal fluid additive supply channel, with each of the ribs having an internal fluid additive or extending along an axial length of the rib that is in fluid communication with the channel and with the interior of the passageway. Communication between the channel and the interior of the passageway is achieved through a suitably configured aperture located along a central portion of the downstream portion of the rib and spaced transversely from the interior wall of the passageway. The aperture may be configured as an elongated slot.
Downstream-extending fins can be located between the interior wall of the passageway and the ends of the aperture or slot aperture. Typically, a pair of such fins will be provided for each elongated slot aperture for preventing fluid injected through the opening or slot and into the viscous fluid food flow within the passageway from contacting the interior wall of the passageway. In this manner, unwanted pooling or accumulation of the fluid additive along the wall of the passageway is prevented. Such pooling or migration to the interior wall of the passageway is undesirable because it is very difficult to properly mix, thereby creating undesirable concentrations of the additive fluid in such areas.
In accordance with another aspect of the present invention, the passageways in the fluid injector device are straight and have an exterior line of sight access to permit such passages to be readily cleaned. This is particularly advantageous for various types of food materials that become hardened and have a strong adherence to metal parts, including cooked and dried cereal dough.
Preferably, the ratio of the interior diameter of the passageway to fin width is in the range of from about 6 to about 10 and the ratio of the interior diameter of the passageway to the fin length is in the range of from about 3 to about 15.
Typically, the ribs have an internal passageway or bore that extends along an axial length of each rib that is relatively large in volume compared with the area of the aperture through which the fluid additive can be injected into the passageway. Such an arrangement facilitates the relatively uniform discharge of fluid throughout the length of the aperture or apertures located in the rib.
In accordance with another aspect of the present invention, a system is provided for dispersing a fluid additive into a relatively viscous fluid food flow stream. The system comprises a passageway having an interior and an exterior and including an interior wall. The passageway is suitable to accommodate a fluid food flow through the interior of the passageway. A fluid additive injection device is associated in an operative relation with the interior of the passageway for injecting a fluid additive into a fluid food flow in the passageway. The fluid additive injection device includes a fluid additive manifold, a plurality of elongated ribs extending from the manifold and which extend transversely across at least a portion of the passageway. The manifold has an internal fluid additive supply channel and each of the ribs has an internal fluid additive bore extending along an axial length of the rib in fluid communication with the channel and with the interior of the passageway through a rib aperture preferably located along a central portion of the downstream surface of the rib, face or portion, which aperture is spaced transversely from the interior wall of the passageway. A fluid additive supply source is in fluid communication with the fluid additive manifold. A pump is provided for supplying a constant amount of fluid additive from the supply source to the manifold without utilizing a flow control valve. This can be accomplished in a number of ways, including utilizing piping of equal length and diameter from the pump to each of a plurality of injection devices that may be utilized. Finally, a fluid food mixer is disposed in the passageway downstream of the food additive injection device for mixing the additive to a desired degree. In accordance with the present invention, incomplete mixing is contemplated to provide a swirled or marbled effect or varied concentration of the fluid food additive, which may be a colorant.
In accordance with another aspect of the invention, a fluid food flow stream, which may be obtained from the outlet of a food extruder, is directed to the system in accordance with the invention which can include structure for splitting the main flow stream into a plurality of substreams for further processing, including the introduction of a desired fluid additive. In connection with this aspect of the invention, a plurality of passageways can be provided with each passageway having one of the fluid additive injection devices. Structure is provided for supplying an equal amount of the fluid additive to each of the additive injection devices without a flow control valve or other adjustable flow control structure or mechanism.
In accordance with another aspect of the invention, the structure for supplying the fluid additive to each of the additive injection devices includes a piping system and a single pump. The piping system is in fluid communication with each of the manifolds of the fluid additive injection devices, including a separate delivery pipe to each manifold, with the piping system being configured so that the flow rate of the fluid additive at a given pump output is the same to each manifold.
In accordance with another aspect of the present invention, a plurality of passageways, each containing a fluid additive injection device, is provided, which may be an even number of passageways with a separate pump and piping system supplying a single pair of fluid additive injection devices.
In accordance with still another aspect of the present invention, a method of injecting a fluid additive into a relatively viscous fluid food stream traveling in a passageway is provided. The passageway has an interior wall in which the injected fluid additive avoids contact on the interior wall of the passageway. In accordance with the method, a fluid additive injection device is provided and associated in operative relation with the passageway for injecting the fluid additive into the fluid food flow. The injection device can be as previously described and may include a fluid additive manifold, a plurality of elongated ribs extending from the manifold and which extend transversely across at least a portion of the passageway. The manifold may have an internal fluid additive supply channel, with each of the ribs having an internal fluid additive bore that extends along an axial length of the rib in fluid communication with the channel and with the interior of the passageway through a rib aperture located along a central portion of the downstream portion of the rib and spaced transversely from the interior wall of the passageway. In addition, a pair of elongated fins may be associated with each rib and disposed between the interior wall and the end of a rib aperture, which fins extend downstream of their respective rib for preventing fluid injected through the slot from the manifold and into the passageway from contacting or pooling along the interior wall of the passageway. The method further includes passing the relatively viscous fluid food through the passageway and injecting a fluid additive into the fluid additive injection device, through the rib apertures of the injection device and into the viscous fluid food, the fins preventing the fluid additive from contacting or pooling along the wall of the passageway.
In addition, the present invention provides for a system and method of introducing a uniform amount of additive across a plurality of subflow passageways. A positive displacement pump capable of generating pressure in excess of each subflow passageway is connected between the additive source and each additive injection cartridge located in the subflow passageways. Tubing or piping between the pump and each subflow passageway may include a suitable restriction or fixed diameter for adjusting the pressure drop between the pump and each additive injection cartridge. For example, a narrow diameter tube diameter could be used to connect the pump to a subflow passageway that is located closer to the pump than another subflow passageway located further from the pump wherein a wider diameter tube or pipe could be used to connect the pump to the longer subflow passageway. Consequently, the additive flow rate into each additive injection cartridge can be uniform without a flow control valve. This ensures that the amount of additive dispersed throughout each extrudate subflow is the same, thereby producing a uniform food product yield from the plurality of subflow passageways.
Alternatively, the fluid additive delivery system can consist of a relatively large diameter pipe that supplies the individual injector cartridges. Preferably, any piping that connects the large diameter pipe with the individual injector cartridge is of relatively the same length and diameter.
Alternatively, when a uniform additive blend across all extrudate subflows is not desired, one embodiment of the present invention provides for a plurality of pumps wherein the number of pumps is at most one less than the number of subflow passageways. Here, the pressure drop across each additive injection cartridge need not be uniform. With this arrangement, one pump can provide additive to two or more subflow passageways. Thus, different additives may be introduced to different subflow passageways or varying amounts of the same additive may be introduced to different subflow passageways.
The present invention further provides for an additive injection cartridge that uniformly disperses additive throughout each corresponding extrudate subflow. The additive injection cartridge may be disk-shaped and partitions the extrudate subflow by means of a plurality of parallel ribs which are positioned perpendicular to the direction of the extrudate subflow in each passageway. In a preferred embodiment, the upstream surface of each rib comes to a point wherein the apex of the point partitions the oncoming subflow. This apex reduces the friction between the ribs and the subflow during partitioning, thereby assisting to reduce the pressure drop across the additive injection cartridge.
Another aspect of the invention provides fins on the downstream surface of each rib. These fins are important in restricting the migration or flow of the additive fluid to the exterior of the food stream before the extrudate-additive combination reaches the static mixers.
According to a further aspect of the present invention, bores within the ribs extend through the disk with orifices on each end. This allows for easy maintenance and cleaning of the rib interior.